4io 
variations are not accidental, this shows that they have 
not occurred among variations inevitably associated with 
sexual reproduction. If the change is due to the sensitive 
response of the organism, acted upon by external con 
ditions, these are not the variations from which Natural 
Selection professes to select. With respect to the relative 
part which Natural Selection plays in comparison with the 
direct action of the environment, it is obvious, to say the 
least, that the more there is done by external condition, 
the less will be left to do by Natural Selection. How 
selection can act on forms best capable of responding to the 
requirements of new conditions—if that means a mere 
potency, and not an actually achieved change, more or less 
—appears to me utterly inconceivable. 
A third test is based upon the utility of the variation. 
Mr. Darwin declares that transforming influences produce 
useless variations and cannot produce useful variations 
in face of changed conditions. On the other hand, he 
contends that Natural Selection cannot produce useless 
variations, but that all useful variations are the result of its 
action. But, at the same time, he warns us that it is not 
always easy to say how much is due to Natural Selection, 
or how much to transforming influence. 
Mr. Darwin frequently insists on the fact that trans 
forming influences produce unuseful variations. 
“No doubt the definite action of changed conditions and the 
various causes of modifications, lately specified, have all produced an 
effect—probably a great effect—independently of any advantage.”— 
(Origin of Species, p. 160.) 
“ In many other cases modifications are probably the direct result of 
the laws of variation or of growth, independently of any good 
having been thus gained.”—(Origin of Species, pp. i6y-6.) 
“As these variations seem of no special use to the plants, they 
cannot have been influenced by Natural Selection.”—(Origin of 
Species, p. 174.)